#!/usr/bin/perl -w

 print "Please input the width of the base (1-50) > ";
 chomp(my $input = <STDIN>);
 if ($input < 1 or $input > 50) {
 die "Input must be in the range (1..50)!\n";
 }

 {
 my ($trend, $i) = (0, $input);
 while ($i <= $input) {
 if ($i == 1 or $i == 2) {
 $trend = 1;
 }
 print " " x (($input - $i)/2) . "*" x $i . "\n";
 } continue {
 $i += ($trend? 2 : -2);
 }
 }